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Neurophysiological Pathways to Obesity Below Awareness and Beyond Individual Control

Aug 5, 2008

Our new intern, Kate Messamore, PharmD Candidate, University of Florida has reviewed Neurophysiological Pathways to Obesity: Below Awareness and Beyond Individual Control written by Deborah A. Cohen, MD, MPH, at the RAND Corporation. This is some unbelievable information you have to read.

Neurophysiological Pathways to Obesity Below Awareness and Beyond Individual Control
Written byDeborah A.Cohen, MD in Diabetes 57:1-5, 2008
Reviewed by Kate Messamore, Doctor of Pharmacy Candidate, University of Florida College of Pharmacy

Have you ever thought that you may be addicted to chocolate?  Or, while you are dedicated to maintaining a healthy diet, you still find yourself craving McDonalds?  Well, according to the article Neurophysiological Pathways to Obesity Below Awareness and Beyond Individual Control by Deborah A.Cohen (Diabetes 57:1-5, 2008), the reasons for these feelings and behaviors may be out of our control.  Interestingly, the author proposes that there may be chemical mechanisms responsible for the overwhelming trend of increasing obesity in nations across the world.  She refers to several possible pathways which support the theory that obesity is a result of automatic responses to our environment.

The first mechanism addresses the chemical response in the brain to food and images of food.  Much like the brain’s reaction to the sight of drugs by drug addicts, studies have shown that dopamine is secreted in response to people being shown a picture of food.  The release of dopamine results in food cravings and motivation to eat.  Considering the amount of food advertising present in most public places, it would be difficult to avoid this dopamine stimulation.

In addition, the article cites the fact that people have a natural, inborn preference for sugar and fat above other types of food.  This is because these types of food provide a quick source of energy.  Fats are also said to activate the brain’s reward system.  Unfortunately, it seems that due to the high profitability of these items, there is extensive marketing to encourage impulsive behavior in buying these products.  An example is the placement of these items at the checkout line while waiting to buy groceries.

A third theory is that the increased trend of obesity is due to hardwired behaviors resulting from our evolution from hunters and gatherers.  In early times, humans gathered as much food as possible when it was available.  Also, a great variety of food was important because then more nutrients were obtained.  The current food industry takes advantage of this instinct by providing an abundance of low-nutrition snack foods in an endless variety.  The article states that more that 10,000 new processed foods are introduced annually.  In addition, studies have shown that people will consume greater quantities when they are provided with larger quantities of food.  In response, grocery stores stock shelves with large amounts of these snack foods and beverages to promote greater consumption.

According to the article, studies have shown that humans are unable to estimate volume and portion size by the appearance of the food.  They also cannot accurately estimate the caloric content of food by appearance.  This can be a problem, because portion sizes served by restaurants have been increasing dramatically for decades.  Often, the current portion sizes provide two to five times more calories that what is needed.

The natural tendency of humans to conserve energy is the fifth proposed mechanism in the article.  Since humans are hardwired to search for shortcuts and labor-saving methods, we are drawn to food that is convenient and fast. 

Unfortunately, fast food is one of the biggest contributing factors to the obesity epidemic.

The sixth mechanism is described as mirror neurons, which are related to imitative behaviors.  This begins by children learning from adults by mimicking, and continues throughout life.  This is apparent by people unconsciously mimicking other people’s eating behaviors.  The article states that studies have shown that obesity is contagious within social networks, and that people tend to consume more during a meal when there are more people present.

The author also theorizes that eating behaviors may be influenced by stereotypes.  Many advertisements associate food with other human wants and needs.  They also customize marketing so that it reflects the target groups.  Another marketing technique is called priming.  This method uses images, sounds, smells, and lighting to increase food consumption.  For example, playing slow music in a restaurant has been shown to increase the amount of time that diners stay at their table, while fast music decreases the time spent.

The last mechanism contributing to obesity is that humans have limited cognitive capacity and self-regulatory control.  When we are overloaded with information, people tend to make impulsive decisions.  Many people find nutritional labels to be overwhelming, and make poor eating choices when they cannot decipher the information on the label.

The author makes some very interesting points in this article that may explain part of the reason why obesity is growing at such an alarming rate.  She proposes that society must understand these issues that humans will always have to deal with in order to overcome this epidemic.  This article makes so much sense that  more research needs to be done in order to tackle the issues of food availability, portion sizes, and advertising.